Keep in mind that in order to one hit both husks and parasites, your max hit has to equal or be above their health (20 and 55 HP respectively) The strength level above is an appoximation. This will change depending on the equipment you decide to use. You can calculate your max hit using this link, simply enter your equipment and set the husk and parasite as your monster! https://gearscape.net/calculators/dps The OSRS Wiki has a great section on the recommended equipment! https://